Trout hit .531 as a high school senior, with 18 home runs in 81 at-bats and 20 steals. Baseball America named him a high school All-American outfielder alongside Max Walla and Randal Grichuk. The Los Angeles Angels of Anaheim took him 25th overall in the 2009 amateur draft, one pick after they took Grichuk. Mike was the only player on stage when Major League Baseball televised the first round of the draft for the first time ever. Trout signed for a $1,215,000 bonus.

Trout started the 2011 season with the AA Arkansas Travelers, where he hit .330 with 9 homers, 11 triples, 27 RBI and 28 stolen bases in 78 games over the first half of the season. On July 7th, the Angels announced that he was being called up to the big leagues and would make his major league debut the next day, following a hamstring injury to rookie centerfielder Peter Bourjos. At 19, Trout was the youngest player in the major leagues. "Mike Trout has a chance to be a special player," Angels manager Mike Scioscia stated. "He can really run, and he loves to compete. He has all the tools and the desire to make things happen."

He went 0 for 3 in his debut against the Seattle Mariners, but made a great running catch in the 9th inning with the game tied, depriving Franklin Gutierrez of an apparent double. He hit his first major league home run on July 24th, a three-run shot against the Baltimore Orioles'Mark Worrell that broke open the game in the 8th inning, leading to a 9-3 Angels win. He was the first teenager to hit a major league homer since Justin Upton in 2007. With Bourjos again healthy, Trout was sent back to Arkansas on August 1st, having gone 7 for 43 with a homer and 6 RBI in his first taste of major league action.

After a few weeks in the minors, Trout was brought back up to the majors. Scioscia had talks with Bobby Abreu and Vernon Wells, apparently indicating that they would have less playing time as a result. On August 30th, Trout showed that it would be hard to dislodge him from the starting line-up from now on with a great performance against the Mariners; he hit two homers and drove in 5 runs that day. Both homers came off Anthony Vasquez, making only his second career start. At the conclusion of the minor league season, he was named by Baseball America as its Minor League Player of the Year, succeeding Jeremy Hellickson. For the year in Arkansas, he had hit .326/.414/.544, with 18 doubles, 13 triples, 11 homers and 33 steals in a tremendous all-around performance while one of the youngest players in the circuit. In the majors, Trout played in 40 games with a batting line of .220/.281/.390; he hit 6 doubles and 5 homers, and played all three outfield positions.

Mike Trout showed up in spring training in 2012 with a mysterious illness. He had lost 15 pounds and was too weak to play in the initial Cactus League games. The Angels described the illness as a type of flu bug or virus. Trout was taking medication although doctors could not pinpoint the exact condition, after ruling out a thyroid disorder or Valley Fever. The result was that his chances of making the big league team shrank to nothing, and he was assigned to the AAA Salt Lake Bees to start the season. He did not stay in Salt Lake long, though. The Angels got off to an unexpectedly rough start, and on April 27th made a couple of moves to shake the team, including releasing 17-year veteran Bobby Abreu and swallowing the remainder of his contract, and calling up Trout to Anaheim. He justified the Angels' confidence in him by winning American LeagueRookie of the Month honors for May and the team began to play at the level that had been anticipated. During the month, he hit .324 with 6 doubles and 5 homers, 16 RBI and 21 runs scored. On June 27th, he made what was widely described as the "catch of the year", robbing the Baltimore Orioles'J.J. Hardy of a home run at Camden Yards by extending his glove a foot and a half over the center field fence and reeling in his the ball; his feet were a good two feet above the ground when he made the catch, his back against the wall. Inspired by his great play, the Angels won the game, 13-1. For the second consecutive month, Trout was named the AL Rookie of the Month for June, after hitting .372 with 7 doubles, 27 runs and 16 RBI. If that wasn't enough, July was even better. First he was named to the All-Star team, then set an American League rookie record with 10 homers during the month, and tied Hal Trosky's record, set in 1934, with 32 runs scored. Only one other player in major league history - the great Rickey Henderson - had ever finished July with a .350 batting average, 15 homers and 30 steals: he was at .353, with 18 homers, and leading the majors in runs with 80 and steals with 31, numbers worthy not just of a Rookie of the Year but of an MVP candidate as well. Indeed, when Major League Baseball handed out its monthly honors at the end of July, he was both the AL's Rookie of the Month and Player of the Month, becoming the first player in the junior circuit to ever win both awards in the same month. He hit .392 in addition to his record numbers of homers and runs scored, and drove in 23 runs in 25 games, while stealing 9 bases. He also set an American league rookie record by scoring a run in 14 straight games that July; it was also a franchise record for all players. On August 23rd, he became the youngest player to record 20 homers and 40 steals in a season, when he swiped his 40th base in a 14-13 win over the Boston Red Sox, bettering by 6 months a record set by Cesar Cedeno in 1972. He repeated as AL Rookie of the Month in August, having hit .284 with 7 homers, 26 runs, 19 RBI and 11 stolen bases. On September 30th, he became the first rookie ever to have both 30 homers and 40 stolen bases, when he hit his 30th long ball off Yu Darvish of the Texas Rangers; he still had a chance to become only the third player in major league history with 30 homers and 50 stolen bases in a season, after Eric Davis and Barry Bonds, needing only two more steals to do so, but he finished one shy, at 49, still enough to lead the AL. He also hit .326, led the AL with 129 runs, had 27 doubles, 8 triples and 30 homers, and drove in 83. He had the 5th-best Wins Above Replacement (10.7) by a player under 25 years of age in baseball history, behind Babe Ruth (1920), Lou Gehrig (1927) and Mickey Mantle (1956 and 1957). Had it not been for the Triple Crown won by the Detroit Tigers'Miguel Cabrera, he would have been a certain winner of the AL MVP Award, but the result was uncertain given the historic nature of Cabrera's feat. Unsurprisingly, he was an unanimous choice to win the 2012 American League Rookie of the Year Award, the youngest player ever to take the award, surpassing Lou Whitaker (although National League winner Bryce Harper was even younger.

In spite of Trout's tremendous rookie season, the Angels decided to play hardball when it came to setting his salary for 2013. Taking advantage of the fact he was not eligible for arbitration, they set his salary at $510,000, just $20,000 above the minimum salary, a unilateral move which his agent, Craig Landis, found very upsetting. As he stated: "In my opinion, this contract falls well short of a 'fair' contract, and I have voiced this to the Angels throughout the process." Another upsetting issue was that the Angels had decided to move Trout from centerfield to left, leaving center for Peter Bourjos, and placing free agent signee Josh Hamilton in right field. Trout started the year relatively quietly, as did the Angels, who failed to get off to a strong start. After 44 games on May 21st, he was hitting only .278, but 23 extra-base hits and as many walks meant that his OPS+ was still an excellent 123. That night, he hit for the cycle for the first time of his career, collecting 5 RBIs to lead the Angels to a 12-0 rout of the Seattle Mariners. He was the 6th player in Angels history to hit for the cycle, and the first since Chone Figgins in 2006. Trout also became the youngest player in AL history to hit for the cycle. On September 17th, Trout became the first player in American League history to amass 25 home runs, 30 stolen bases, and 100 walks in a season. He finished the year at .323/.432/.557 in 157 games, with 39 doubles, 9 triples and 27 homers. His 109 runs scored led the AL, as did his 110 walks and he drove in 97 runs in spite of batting first and second until early August, when he was moved to the third slot. His OPS+ of 179 was even higher than in his rookie season, but was second to Cabrera, who also followed his Triple Crown season with another great year; Cabrera again won the MVP Award and Trout again finished second.

The Angels were more generous with Trout in term of contract before the 2014 season: the one-year $1 million contract they offered him in spring training was the highest ever for a player not yet eligible for arbitration, as both Ryan Howard and Albert Pujols had both made $900,000 in their final season prior to arbitration. The question now was when the Angels and Trout would agree on a contract to take him through his six arbitration years, with $150 million the figure being quoted by reporters. On March 28th, the two sides did come to an agreement, for $144.5 million; however his contract was dwarfed by Miguel Cabrera's record-breaking $292 million deal signed the same day. For all his excellence over his first two full seasons, there was one feat Trout had not accomplished, which was to hit a walk-off homer. He put an end to that on May 15th when he connected for a three-run shot off Brad Boxberger of the Tampa Bay Rays, giving the Angels a 6-5 win. He was named the AL Player of the Month in June, when he hit .361 with 10 doubles and 7 homers, 20 runs scored and 21 RBIs. He was voted to start the 2014 All-Star Game and put on a show at the mid-summer classic held at Target Field in Minneapolis, MN on July 15th: in the 1st inning, he tripled off Adam Wainwright with Derek Jeter on board to drive in the game's first run, then came in to score on Miguel Cabrera's homer; in the 5th, he doubled off Pat Neshek to drive in Derek Norris with what would prove to be the winning run in a 5-3 win. He was voted the game's MVP as a result. While his batting average was down compared to his first two seasons, he was still an offensive juggernaut, and this time, he was not alone, as the Angels surged to first place in the AL West when the Oakland A's hit a rough patch in late August. He topped 100 RBIs for the first time while also setting a career high for homers, and when he scored his 100th run on September 10th, he became only the 6th player to have done so three times by age 23 (Mel Ott, Buddy Lewis, Ted Williams, Vada Pinson and Alex Rodriguez were the others). He finished with 111 RBIs, the most in the AL, 36 homers and a .287 average. In his first taste of the postseason, however, he was limited to 1 in 12, the hit being a homer, while the Angels were swept by the Kansas City Royals in the ALDS. He was rewarded for his outstanding season by winning the AL MVP Award by unanimous vote.

On April 17, 2015, he hit two homers in a 6-3 win over the Houston Astros, which gave him 101 homers and 104 stolen bases and made him the youngest player ever to top three figures in both statistics, breaking the mark set by Alex Rodriguez. He was again voted a starter in the All-Star Game and made the contest his personal stage when he became the first repeat winner of the game's MVP Award, thanks to a home run off Zack Greinke that led off the game, and scoring the go-ahead run for the American League in the 5th inning in his league's 6-3 win. In the first game of the second half on July 17th, he hit a walk-off homer off Koji Uehara of the Boston Red Sox with two outs in the 9th to give the Angels a 1-0 win. He injured his wrist later in the month in attempting to make a diving catch on July 26th, however, forcing him to miss a game and undergo an MRI on July 28th. He succeeded teammate Pujols as AL Player of the Month in July after hitting .367 with 12 homers, 20 runs and 26 RBIs. On September 26th, he made a tremendous leaping catch over the center field fence at Anaheim Stadium, jumping a good three feet above the fence with his back to the plate to deprive Jesus Montero of the Seattle Mariners of a three-run homer. That catch was immortalized on a Toppsbaseball card, card number 1 of the 2016 set. He finished the season with a .299 average, a league-leading .590 slugging percentage, 104 runs, 41 homers, 90 RBIs and 92 walks. His OPS+ of 176 was also tops in the league.

The Angels had a dreadful season in 2016, but Mike was just about the lone bright light in the firmament. On August 15th, he stole his 20th bases of the year to join the 20-20 club for the third time, becoming the 7th player in major league history to do so. On August 31st, he was involved in a three-vehicle crash on a freeway in the Los Angeles area. With traffic stopped due to a collision ahead, Trout stopped too late and his car hit the back of a stopped vehicle ahead, sending it crashing into a truck. Trout escaped without being hurt, but the female driver of the second car suffered what police described as "major injuries". He finished the season with a .315 average, 29 homers and 100 RBIs to go along with an American League-leading 123 runs, 116 walks and a .441 OBP. He received his fifth straight Silver Slugger Award and in a tight race, won his second MVP Award over Mookie Betts of the Boston Red Sox.

Mike started off 2017 by being named the AL Player of the Month in April, on the strength of a .364 average, 18 runs scored, 7 homers and 18 RBIs. On May 28th, he was leading the majors with 16 homers when he sprained his thumb while stealing a base in a game against the Miami Marlins and had to leave the game. He was placed on the disabled list for the first time of his career the next day as he had to undergo surgery on the thumb. In spite of having played only two months, he was voted a starter on the All-Star team, his sixth nod for the Midsummer Classic, but he had to miss the game as he was not yet fully healed. He did return to action in the Angels' first game after the break, on July 14th. On August 7th, he collected his 1,000th hit on his 26th birthday and also homered for his fourth birthday homer in six big league seasons, but the Angels still lost to the Baltimore Orioles, 6-2. Only Mel Ott, Jimmie Foxx and Mickey Mantle, in addition to Trout had compiled 1,000 hits, 500 runs and 500 walks by the end of their age 25 season - pretty hallowed company. He was also only the 5th player to record 1,000 hits and 190 HRs by his 26th birthday, joining Foxx, Ott, Mantle, and Alex Rodriguez, although he had played less career games than the other four. He ended the year at .306 with 33 homers and 92 RBIs, his injury having cost him a shot at another MVP Award (he finished 4th in the voting). He led the AL in both OBP (.442) and slugging percentage (.629), resulting in his also winning the OPS (1.071) and OPS+ titles (187).

Trout was slated to earn a salary of $34.083 million in 2018, making him the highest-paid player in baseball, ahead of Clayton Kershaw and Zack Greinke. On May 26th, he had the first five-hit game of his career to lead the Angels to an 11-4 win over the New York Yankees; he had a single, three doubles and a two-run homer while driving in 4 runs. The homer was his 17th of the season, tying him with Mookie Betts for the AL lead. On June 21st, he played his 1,000th game, and in typical fashion drew 3 walks and scored 2 runs in an 8-5 win over the Toronto Blue Jays. He was on a scorching run, with a .640 average and 4 homers over his last 9 games. He continued to build on his résumé as one of the greatest performers in the history of the All-Star Game when he drew a walk off Max Scherzer and homered off Jacob deGrom in the 2018 contest, in his 7th participation on July 17th at Nationals Park. Before the game, Commissioner Rob Manfred had pointed out in a town hall meeting that while many observers recognized Trout as the greatest player of the moment, he was not one to get on board with major initiatives to market himself and the sport to a broader or younger audience. The Angels replied by stating that they were happy with Mike's stance and desire to "prioritiz(e) his personal values over commercial self-promotion," and praised the time he devoted to community outreach, such as visiting children's hospitals and schools. In any case, he had his customary excellent season, finishing it off by being named the Player of the Month in the AL for September, when he hit .329 with 8 homers and 16 RBIs. That gave him season's totals of .312, 39, 79, in addition to leading the league in walks (122), OBP (.460) and OPS (1.088).

On March 19, 2019, he signed a ten-year contract extension that would pay him $426.5 million through 2030, although the official announcement had to wait a few days.

Trout's brother-in-law, Aaron Cox, pitched in the Angels' chain in 2015-2016 and 2018.